A thief struck a man on the head before stealing his car.
The victim had started the engine of his silver Mercedes, on his driveway in Mansfield Road, Killamarsh at 7.20am.
While he was spraying deicer on to the vehicle he was struck on the back of the head.
The thief, described as in his 20s, white, 5ft 11ins, wearing a dark carky jacket with the hood up and dark jeans, then jumped in to the car and drove off.
The victim was not injured.
Witnesses should call police on 101.